David, I just measured my 35 for you, here they are for you

bottom of the Case to the top of the head Fins... 5&3/4 inches,,, measured at the back of the engine..
Cylinder Head diameter... 2&3/4 inches,
Crank Shaft Length.. just over 2&1/2 inches, measured from the Case, NOT the Prop Drive
Carb Number.. WT561 (450),

as I compare your Carb to mine, I think your engine is the 35cc,,, you should keep it, it's a very good engine, and if you update it with a newer CH Ignition it will even be a better engine.

BTW, after that engine has sat a while, I had found that you should power up it's Ignition and let it set a while before trying to start it, maybe 3, 4 or 5 minutes or so.

Jim